I'm finding far too many variables floating around in my grey-matter, causing me to go off at tangents researching multiple different options of anything and everything, so am taking some decisions to lessen the load on my limited mental capacity.

Have decided on the adjustable bed type design similar to Iwant1's, but will do the initial build on a flat aluminium frame in the caravan, and only weld up the steel frame when I eventually get it into a workshop before using it in anger.

As I don't have machining facilities in said caravan, have bought a set of pre-machined ballscrews from linearmotionbearings2008 for about £330+duty:

- 4pcs anti backlash ballscrews
- RM1605-300/850/1150/1150mm-C7 (4 screws+4 balnuts+4endmachinings)
- 4 sets BK/BF12 with locknut and circlip
- 4pcs of 6.35mm*10mm flexible couplings

Have also roughly decided on using the following, but will only buy these later:

- SBR20 supported rails and SBR20UU blocks for all three Axes
- PM752 drivers x 4
- 3Nm NEMA23 steppers x 4 (SY60STH88-3008B ?)
- Mach3
- Ethernet SmoothStepper

Meantime, I will work on the rough design in SketchUp, thanks to the help from the forum, and only determine exact dimensions when the ballscrews arrive.

Btw, many thanks to JAZZCNC for giving me plenty of time and great info!